CVE-2026-118174

Displaying a message could load an attacker-chosen URL through an OpenPGP key attachment

Published Oct 27, 2026 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
Description
When a message containing an OpenPGP key attachment was displayed, Thunderbird automatically loaded the attachment's content to offer importing the key. A sender could mark the attachment as an external attachment pointing to an arbitrary URL, which Thunderbird then loaded without any user interaction, bypassing remote content blocking. On Windows, a URL pointing to an attacker-controlled network share could leak the user's NTLM credentials.
The NTLM credential leak only affects Thunderbird on Windows. On other operating systems, the issue allowed a remote request that bypassed remote content blocking. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4877-1 thunderbird security update
History
Type Values Removed Values Added
Weaknesses CWE-829
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N'}

Type Values Removed Values Added
Weaknesses CWE-918
References
Metrics threat_severity

None

cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N'}

threat_severity

Moderate

Type Values Removed Values Added
Weaknesses CWE-598
CWE-601
Type Values Removed Values Added
First Time appeared Mozilla
Mozilla thunderbird
Vendors & Products Mozilla
Mozilla thunderbird
Type Values Removed Values Added
Description When a message containing an OpenPGP key attachment was displayed, Thunderbird automatically loaded the attachment's content to offer importing the key. A sender could mark the attachment as an external attachment pointing to an arbitrary URL, which Thunderbird then loaded without any user interaction, bypassing remote content blocking. On Windows, a URL pointing to an attacker-controlled network share could leak the user's NTLM credentials. The NTLM credential leak only affects Thunderbird on Windows. On other operating systems, the issue allowed a remote request that bypassed remote content blocking. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.
Title Displaying a message could load an attacker-chosen URL through an OpenPGP key attachment
References

Sources

Status
PUBLISHED
Assigner
mozilla
Published
Updated
Nov 4, 2026, 4:50 PM
Reserved
Oct 27, 2026, 6:16 PM
Status
Deferred
Published
Oct 27, 2026, 7:17 PM
Modified
Nov 4, 2026, 5:17 PM
Severity
Moderate
Public date
Oct 27, 2026, 6:16 PM